Creating this post for anyone that had to update node and ran into issues in their existing sage projects. (i.e. I updated node since I just had to play with phoenix/elixir). Just some quick fixes:
1 - If you’re getting these errors it stems from an incompatibility with npm and later node versions, so we must update npm:
Delete your current ~/.npm folder rm -rf ~/.npm
Install latest NPM: npm install -g npm@latest
May need to: sudo chown -R $(whoami) /usr/local/lib/node_modules/
Delete your current sage/node_modules folder
run npm install from sage directory again
Side note: having upgraded from a 0.12 version of node, the gulp build process SEEMS faster, unfortunately I’m unwilling to confirm at this time. 
Side note 2: there is a new progress bar on npm, woo.
2 - With the latest node (6.5, apparently anything above 5.5) you’ll run into this issue where gulp mistakenly looks for LESS files instead of SASS files: Compiling new scss, error .less not found - #8 by jasperfrumau | https://github.com/roots/sage/issues/1648
Assuming you use SASS, this is a problem. You can fix this on a per-project basis by commenting out these lines in your gulp file:
.pipe(function() { return gulpif('*.less', less()); })
OR you can update gulp-if to this version in your package.json file:
"gulp-if": "^2.0.1",
then run:
npm update in your sage directory
